The invention relates generally to golf putters and more particularly to golf putter heads having a cavity filled with a lightweight polymer. Such a construction for a golf putter head can provide an enlarged putter head, a high rotational moment of inertia across the striking surface of the putter, a thicker, reinforcing rearwardly extending flange, improved dampening of vibration and a deadened sound upon impact with the ball, all of which combine to produce a more forgiving putter that is easier to align and has a more solid feel when striking the ball.
In order to putt a golf ball accurately, it is first necessary to align the putt properly, keeping the striking surface of the putter perpendicular to the line of the putt. It is important to keep the striking surface perpendicular to the putting line during the impact portion of the stroke, and to strike the ball with the optimum portion of the striking surface, known as the sweet spot, for transferring energy to the ball. The sweet spot is generally located around the center of mass of the putter head. Accuracy and effectiveness of the putt depends on the amount of energy transferred from the putter head to the ball and minimizing the amount of energy lost due to vibration and twisting of the head during impact.
As the striking surface meets the ball, there is a tendency for the putter head to twist if the ball is struck away from the center of mass of the putter head. This can severely decrease the accuracy of the putt. In order to reduce the effect of off-center hits, numerous putters have been designed with weights in the heel and toe of both normal sized putters and oversized putters to increase the putter head""s rotational moment of inertia.
It is also desirable to minimize the loss of energy due to vibrations upon impact or to dampen these vibrations. This produces a more xe2x80x9csolid feelxe2x80x9d when the striking surface meets the ball. Some prior art putters have attempted to reduce the vibration created when striking a ball by inserting a polymer in a shallow cavity along the striking surface of the blade. This, however, does not significantly displace enough heavy material to enable an oversized putter head to be made properly, nor does it significantly change the inertia properties of the putter head. The prior art methods also make it difficult to construct an oversized putter head with thick enough sections to reduce vibrations, since the larger the putter head, the thinner the remaining metal structure must be. Exposing the polymer on the striking surface may alter the sound made when striking the ball, but also provides a surface that is more prone to wear unevenly, producing a concave striking surface which is detrimental to accurate putting. An example of this type of construction is the Odyssey putter made by Callaway Golf.
Others have tried to minimize vibrations by providing a solid flange behind the blade of the putter head. One such putter head is described in Long U.S. Pat. No. 4,693,478. These methods are limited to either standard sized putter heads, or putter heads made from combinations of aluminum and other heavier materials. The aluminum used in these constructions is soft and not wear resistant, nor durable in the neck and hosel portions of the putter head.
Still other prior art attempts at constructing oversized putter heads have resorted to large hollowed out portions of the heads making them vibrate upon impact with the golf ball. These prior methods have also produced thin faces and rear flanges due to their construction designs. Examples of such constructions are U.S. Pat. No. 4,655,459, the Macgregor xe2x80x9cResponse LTxe2x80x9d putters, and the Nicklaus Golf Equipment Company xe2x80x9cThe Bear IQxe2x80x9d putter.
In order to execute an accurate putting stroke, it is important that the ball is struck near the center of mass of the putter head. This portion of the striking surface is known as the xe2x80x9csweet spotxe2x80x9d. Striking the ball near the sweet spot assures maximum energy transfer from the putter head to the ball. It is therefore desirable to have a putter with a larger sweet spot. It is also desirable to have a putter head constructed of a strong durable material that resists bending, denting and fracture during use, resists corrosion, is large in size providing easy alignment, and high in moment of inertia about its center of gravity, and dampers vibration caused by impacting a golf ball.
Generally described, the present invention is a golf putter head with a hollow vertical interior cavity between the striking face and blade rear surface of the putter head and a horizontal cavity between the sole surface and upper portions of the putter head behind the blade. In an embodiment of the invention, the vertical and horizontal cavities are filled with a lightweight polymer. By distributing a greater portion of the putter head mass to the toe and heel section of the putter head, the moment of inertia along the striking surface of the putter is increased.
The present invention further provides a putter head with an internal xe2x80x9cL-shapedxe2x80x9d cavity and incorporates a suspended insert in the striking face where the insert is greater than 50% of the striking face area. In an embodiment of the present invention, a horizontal portion of the xe2x80x9cL-shapedxe2x80x9d cavity extends beneath a sighting recess toward the striking face. The vertical portion of the xe2x80x9cL-shapedxe2x80x9d cavity extends between the striking face and sighting recess. In embodiments of the invention, the horizontal cavity may include a plurality of horizontal cavities. In further embodiments of the invention the xe2x80x9cL-shapedxe2x80x9d cavity is filled with a lightweight polymer. In another embodiment of the invention, weights are suspended in the polymer-filled cavities to suppress vibration as well as to provide preferred weighting and mass distribution.
The present invention also provides a golf putter head with an internal cavity behind the striking face, the cavity enclosed on at least one side by an unperforated surface of the rear blade, and the internal cavity having a cross-sectional area of greater than fifty-percent (50%) of the area of the striking face. In an embodiment of the invention, the cavity is filled with a lightweight polymer.
It is therefore an object of the present invention to provide a golf putter head that is easy to align to achieve an accurate putt.
It is a further object of the present invention to provide an oversized putting head constructed of standard materials used in small sized putter heads.
It is a further object of the present invention to provide a golf putter head with a high moment of inertia through the center of gravity of the putter, to resist twisting upon striking the ball.
it is a further object of the present invention to increase the size of the sweet spot on the striking surface of the putter.
It is still a further object of the present invention to minimize energy loss due to vibration while putting.
It is yet a further object of the present invention to provide a putter that makes a deadened, softer sound upon impact with a golf ball.
And further still it is an object of the present invention to provide a putter head that is durable, resistant to bending, dent resistant, and corrosion resistant.
The foregoing objects are accomplished by a putter in which the putter head has a thin metallic outside shell with an internal cavity filled with a lightweight polymer.
In further embodiments of the invention, the striking face includes an insert that is suspended from the putter head and secured in place by the polymer in the cavity behind the striking face. In an embodiment of the invention, an O-ring may be used to position the insert on an insert groove extension.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.